An interesting article by David Owen: Hubris and Nemesis in Heads of Government. While I agree that Blair suffered from a pathological excess of self-confidence, I think Owen goes a bit too easy on our dear departed leader. For example, he states:
"I do believe, in contrast to many of their critics, that Bush and Blair did think gas and chemical weapons could be found inside Iraq in 2003, as did the intelligence services of France, Russia and Israel. They genuinely did fear that these weapons might be used, as gas had been previously used against Iran. They also dreaded the eventual development of Iraqi nuclear weapons."
I'm willing to accept - though not convinced by any means - that in some sense Blair believed in so-called WMD. But to say so without qualification is highly misleading.
As Owen's comments elsewhere in the article suggest, there is such a thing as belief too quickly adopted, on insufficient evidence, or even no evidence. There is also such a thing as a reckless disregard for the truth. And there is an association between habitual lies and self-deceiving fantasy.
My opinion of Blair is that his respect for truth had never been very great, and that his ability even to distinguish truth from falsehood had to an extent been corrupted. He started to believe his own lies, and to that extent they stopped being lies. But as long as some instinctive sense of what was useful influenced the beliefs he adopted, he was in some sense still lying.
But there is an acknowledged association between hubris and incompetence in Iraq mentioned by a number of serious commentators. The restless energy of hubris that constantly intervenes often does so without all the factual information; the excessive self-confidence that does not seek advice or fails to listen to the wisdom of others makes serious mistakes; and along with inattention to detail and focus on the broad brush all combine to associate hubris with incompetence and poor judgement.